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United States Patent |
5,603,377
|
Fujii
,   et al.
|
February 18, 1997
|
Heat pipe and gas-liquid contacting apparatus capable of heat exchange
using the heat pipes and heat exchanger of gas-liquid contacting plate
type
Abstract
A heat pipe includes: a pipe barrel; and a large number of fins disposed on
the peripheral surface of the pipe barrel at least on either a heat
collecting section side or a radiating section side, each of the fins is
attached to the pipe barrel on a plane perpendicular to the axis of the
pipe barrel, and each of the fins is composed of a metal plate and
net-like material adhered to both surfaces of the metal plate.
A heat exchanger of gas-liquid contacting plate type includes: a plurality
of heat transfer plates, disposed vertically at certain intervals,
defining air flow passages therebetween which allow air to rise, and each
of the plates has a heat medium flowing passage thereinside for allowing a
heat medium to flow therethrough while the side surfaces of each of the
heat transfer plates, which define the air flow passages, are adhered with
nets for allowing a liquid to flow downward along the nets and plates.
Inventors:
|
Fujii; Masumi (Osaka, JP);
Suda; Taiichiro (Osaka, JP);
Hotta; Yoshitsugu (Osaka, JP);
Kitamura; Koichi (Osaka, JP);
Jinno; Yukihiro (Osaka, JP);
Mimura; Tomio (Osaka, JP);
Shimojo; Shigeru (Osaka, JP);
Iijima; Masaki (Tokyo, JP);
Mitsuoka; Shigeaki (Hiroshima, JP)
|
Assignee:
|
The Kansai Electric Power Co., Inc. (Osaka, JP);
Mitsubishi Jukogyo Kabushiki Kaisha (Tokyo, JP)
|
Appl. No.:
|
670719 |
Filed:
|
June 21, 1996 |
Foreign Application Priority Data
| Oct 06, 1993[JP] | 5-250418 |
| Oct 06, 1993[JP] | 5-250419 |
Current U.S. Class: |
165/117; 165/116; 165/907 |
Intern'l Class: |
F28D 003/02 |
Field of Search: |
165/104.26,104.21,117,116,115,914,911,907
|
References Cited
U.S. Patent Documents
2536840 | Jan., 1951 | Cornell, Jr. | 165/115.
|
2944966 | Jul., 1960 | Eickmeyer | 165/116.
|
3095255 | Jun., 1963 | Smith | 165/907.
|
3500893 | Mar., 1970 | McReynolds | 165/117.
|
3825064 | Jul., 1974 | Inoue | 165/907.
|
4206807 | Jun., 1980 | Koizumi et al. | 165/104.
|
4585055 | Apr., 1986 | Nakayama et al. | 165/115.
|
4842052 | Jun., 1989 | Gershuni et al. | 165/104.
|
5195578 | Mar., 1993 | Le Goff et al. | 165/914.
|
Foreign Patent Documents |
777156 | Nov., 1934 | FR.
| |
1399841 | May., 1964 | FR.
| |
2416209 | Aug., 1979 | FR.
| |
3610533 | Jan., 1987 | DE.
| |
1256793 | Oct., 1989 | JP | 165/907.
|
8332 | Apr., 1898 | GB | 165/117.
|
316378 | Dec., 1928 | GB | 165/115.
|
0261251 | Mar., 1988 | GB.
| |
Other References
Patent Abstractsof Japan, vol. 6, No. 131 (C-114) Jul. 17, 1982 & JP-A-57
056 035 (Takeda Kimiko) Apr. 3, 1982.
Patent Abstracts of Japan, vol. 9, No. 84 (M-371) Apr. 13, 1985 & JP-A-59
212 692 (Akutoronikusu KK) Dec. 1, 1984.
|
Primary Examiner: Rivell; John
Assistant Examiner: Atkinson; Christopher
Attorney, Agent or Firm: Jacobson, Price, Holman & Stern, PLLC
Parent Case Text
This is a continuation of application Ser. No. 08/319,049, filed Oct. 6,
1994 which was abandoned upon the filing hereof.
Claims
What is claimed is:
1. A heat pipe comprising:
a pipe barrel; and
at least one fin disposed on the peripheral surface of said pipe barrel at
least on either a heat collecting section side or a radiating section
side, each of said fins being attached to said pipe barrel on a plane
perpendicular to the axis of said pipe barrel,
being characterized in that said at least one fin is composed of a metal
plate and net-like material adhered to both surfaces of said metal plate,
said net-like material being defined by a single-core wire mesh or
single-core plastic net.
2. A gas-liquid contracting apparatus capable of heat exchange, comprising:
a large number of heat pipes according to claim 1, wherein each of the heat
pipes comprises:
a pipe barrel; and
at least one fin disposed on the peripheral surface of said pipe barrel at
least on either a heat collecting section side or a radiating section
side, each of said fins being attached to said pipe barrel on a plane
perpendicular to the axis of said pipe barrel,
being characterized in that said at least one fin is composed of a metal
plate and net-like material adhered to both surfaces of said metal plate,
said net-like material being defined by a single-core wire mesh or
single-core plastic net;
said large number of heat pipes being disposed together so that the heat
collecting section of the heat pipes and the radiating section of the heat
pipes are put together, respectively, with the pipe axes being held
horizontally or approximately horizontally so that fins of the heat pipes
are positioned vertically or approximately vertically,
being characterized in that a large number of fins provided on the heat
pipes in at least one of the heat collecting section and the radiation
section serve as gas-liquid contracting wall surfaces for bringing a
liquid flowing downward from a site above the fins into contact with a gas
fed from a site below the fins or from the side of the fins.
3. A gas-liquid contacting apparatus capable of heat exchange according to
claim 2, wherein said large number of fins disposed vertically or
approximately vertically are joined with one another forming vertical
plates so that the large number of heat pipes, while being kept
horizontally or approximately horizontally, are made to penetrate the
vertically or approximately vertically formed plates in at least one of
the heat collecting section and the radiating section where the pipes are
gathered.
4. A heat exchanger of gas-liquid contacting plate type comprising:
a plurality of heat transfer plates, disposed vertically at certain
intervals, defining air flow passages therebetween which allow air to
rise,
being characterized in that each of said plates has a heat medium flowing
passage thereinside for allowing a heat medium to flow therethrough and
the side surfaces of each of said heat transfer plates, which define said
air flow passages, are adhered with nets for allowing a liquid to flow
downward along the nets and plates, said nets being defined by a
single-core wire mesh or single-core plastic net.
Description
FIELD OF THE INVENTION AND RELATED ART STATEMENT
(1) The present invention relates to a heat pipe (a first configuration of
the present invention) and gas-liquid contacting apparatuses (second and
third configurations of the present invention) which are able to perform
both gas-liquid contact and heat exchange simultaneously by utilizing the
heat pipes. More specifically, the present invention relates to a heat
pipe with fins of certain surface structure and to gas-liquid contacting
apparatuses utilizing the heat pipes. The gas-liquid contacting apparatus
of the present invention is able to perform both heat transfer (or
exchange) and gas-liquid contact at the same time, so that the apparatus
lends itself to applications to various fields of chemical engineering
processes.
A heat pipe is able to perform heat transfer between a heat collecting
section (evaporation section or high-temperature side) and a radiating
section (condensation section or low-temperature side) by utilizing the
evaporation and condensation of a heat transfer medium called as an
operating liquid which is confined inside the heat pipe. The heat pipe of
this kind is capable of conveying a large amount of heat in a short period
of time despite that the temperature difference between the two sides is
very small, so that this device has been used in various fields.
Heat exchangers with heat pipes applied thereto may be used for heating
cold air by utilizing, for example, the heat of exhaust gas. In this case,
a large number of heat pipes 41 are put together, as sectionally shown in
FIG. 7, inside a case 44 in the form of panels. Provided on the peripheral
surface of each heat pipe 41 is fins 42 attached at close intervals so as
to enlarge the heat-transfer surface area. The case 44 is parted
vertically at an appropriate level by a partitioning plate 43 so that air
circulating passage for each air is isolated from the other.
The heat exchanger using the heat pipes is desirably mounted in such a
manner that axes of heat pipes are oriented vertically as seen in FIG. 7.
But, even if the heat exchanger is mounted so that the heat pipes are
oriented horizontally as perspectively shown in FIG. 8, heat transfer
inside the heat pipes can be achieved. In the configuration shown in FIG.
8, the case is also separated in the middle into right and left portions
by means of the partitioning plate 43 so that air circulating passage for
each air is isolated from the other.
In the heat exchanger utilizing the conventional heat pipes, typically, two
fluids, different in temperature, are brought into contact with different
sides of a heat pipe or heat pipes which are partitioned by the
partitioning plate 43 as shown in FIGS. 7 or 8, whereby heat is
transferred or exchanged between the two fluids through the heat pipes. In
some cases where the heat exchanger is applied to perform heat exchange in
the heat collecting portion or radiating portion, a liquid has to be made
to flow down from the top in at least one of the two chambers so that the
liquid is brought into contact with a gas supplied from the bottom or side
of the chamber (gas-liquid contact). In such a case, if the prior art heat
exchanger with the heat pipes or the axes thereof being horizontally or
approximately horizontally disposed as shown in FIG. 8 is used as it is,
the fins conventionally used cannot disperse the liquid over the fin walls
enough. As a result, the liquid tends to concentrate on particular spots,
thereby increasing the flowing speed of the liquid. In other words, the
prior art configuration could not allow the liquid to stay on the surfaces
of fins enough long to sufficiently enhance the gas-liquid contact
efficiency.
The present inventors hereof have energetically studied the above problem
and found the fact that heat pipes provided with fins made up of a metal
plate with nets attached onto both surfaces thereof should be markedly
effective in increasing the efficiency of gas-liquid contact and that the
application of the heat pipes to a gas-liquid contacting apparatus of heat
pipe type should impart excellent heat exchange function to the device.
Thus, the present inventors could achieve the present invention.
(2) The present invention further relates to a heat exchanger of plate
type, and more detailedly to a heat exchanger of plate type which is able
to effectively bring a gas into contact with a liquid on the plate
surfaces while performing heat exchange (a fourth configuration of the
present invention).
In typical chemical plants, it is often needed to efficiently bring a gas
into contact with a liquid in a short period of time. This situation is
represented by, for example, the case where CO.sub.2 (carbon dioxide) gas
in a combustion exhaust gas is recollected by an absorbent solution such
as amine aqueous solution. In order to fulfill such demands, the applicant
of the present invention previously proposed a gas-liquid contacting
apparatus which is filled up with a large number of tubular structure
fillers, each having a horizontal cross-section of an arbitrary shape and
wherein inside walls of the tubular structure is vertically arranged
forming gas-liquid contact surfaces so that the gas-liquid contact
surfaces may be disposed in parallel with the flow of the gas and wherein
the liquid supplied from a site above the fillers is made to flow downward
along the gas-liquid contact surfaces while the gas is supplied from a
site under the fillers so as to contact the gas with the liquid by feeding
the gas from a site under the fillers, the apparatus being characterized
in that the gas-liquid contact surface is made up of a plate-like member
with net-like members adhered onto the surfaces thereof (Japanese Patent
Application Hei-5 No. 59844). But, this proposal does not belong to those
publicly known and therefore, is not assumed as the prior art of the
present invention.
In the gas-liquid contacting apparatus of the above proposal, in the case
where the gas is of the combustion exhaust gas and the liquid is of the
amine aqueous solution as stated above, the absorbent liquid is increased
in temperature by the heat of reaction as the liquid absorbs CO.sub.2 gas,
resulting in a decreased reaction rate of absorption. To deal with this, a
separately provided heat exchanger (a cooler) was provided for the
apparatus to properly adjust the supplied absorbent liquid in temperature.
Nevertheless, as flowing downward in the gas-liquid contacting apparatus,
the reacting liquid increases in temperature, so that the equilibrium
constant for the absorption reaction tends to lower, though the velocity
of reaction increases. As a result, only the adjustment in temperature of
the absorbent liquid supplied was not effective enough to afford
appropriate measure for adjusting the reaction rate. As seen in this
example, since, in chemical plants, the gas-liquid contact process
typically involves exothermic and/or endothermic reaction, each step
requires separate cooler, heater, heat exchanger etc., for the liquid
and/or gas used. Further, in view of heat exchange efficiency,
alternatively, in consideration of increase in cost for building the plant
due to the complication of the plant structure as well as due to the
augment of the required space, the improvement of the gas-liquid
contacting apparatus has been earnestly desired.
Under consideration of what is discussed above, the present inventors
hereof have energetically made studies on the apparatus which is able to
perform both gas-liquid contact process and heat exchange process
simultaneously and which is advantageous in view of the heat exchange
efficiency and space saving, and consequently found a heat exchanger
having a certain structure as being extremely effective, to thereby
complete the present invention.
SUMMARY OF THE INVENTION
(1) The present invention provides a heat pipe (a first configuration of
the present invention) and gas-liquid contacting apparatuses (second and
third configurations of the present invention) which present an increased
efficiency of gas-liquid contact and excellent performances in heat
exchanging.
A first feature of the present invention resides in that a heat pipe
comprises: a pipe barrel; and at least one or more fins disposed on the
peripheral surface of the pipe barrel at least on either a heat collecting
section side or a radiating section side, each of the fins being attached
to the pipe barrel on a plane perpendicular to the axis of the pipe
barrel, and each of the fins is composed of a metal plate and net-like
material adhered to both surfaces of the metal plate.
Further, a second feature of the present invention lies in that a
gas-liquid contacting apparatus capable of heat exchange, has a large
number of the above-described heat pipes disposed together so that the
heat collecting section of the heat pipes and the radiating section of the
heat pipes are put together, respectively, with the pipe axes being held
horizontally or approximately horizontally so that the fins of the heat
pipes are positioned vertically or approximately vertically, and a large
number of the fins provided on the heat pipes in at least one of the heat
collecting section and the radiation section serve as to be gas-liquid
contacting wall surfaces for bringing a liquid flowing downward from a
site above the fins into contact with a gas fed from a site below the fins
or from the side of the fins.
Moreover, in accordance with a third feature of the present invention, in a
gas-liquid contacting apparatus capable of heat exchange described above,
the large number of fins disposed vertically or approximately vertically
are joined with one another forming vertical plates so that the large
number of heat pipes, while being kept horizontally or approximately
horizontally, are made to penetrate the vertically or approximately
vertically formed plates in at least one of the heat collecting section
and the radiating section where the pipes are gathered.
In accordance with the first to third configurations of the present
invention, the heat pipe not only performs efficient heat exchange, based
on the principle of a typical heat pipe, between a fluid in contact with
the heat collecting section of the heat pipe and another fluid in contact
with the radiating section, but also can carry out a markedly efficient
gas-liquid contact on the fins since the vertically or approximately
vertically formed fins in at least one of the heat collecting section or
the radiating section are each made up of a metal plate with nets adhered
to both surfaces of the plate.
(2) In accordance with another aspect of the present invention, a heat
exchanger of gas-liquid contacting plate type (a fourth configuration of
the present invention) is provided which can perform both the gas-liquid
contact process and the heat exchange process simultaneously, and is
advantageous in view of heat exchange efficiency and space factor of the
apparatus.
A fourth feature of the present invention resides in that a heat exchanger
of gas-liquid contacting plate type comprises: a plurality of heat
transfer plates, disposed vertically at certain intervals, defining air
flow passages therebetween which allow air to rise, and is constructed
such that each of the plates has a heat medium flowing passage thereinside
for allowing a heat medium to flow therethrough and the side surfaces of
each of the heat transfer plates, which define the air flow passages, are
adhered with nets for allowing a liquid to flow downward along the nets
and plates.
In accordance with the fourth aspect of the present invention, a liquid to
be subjected to the gas-liquid contact flows downward along the nets
adhered to the side faces of the heat transfer plates. In this while, the
liquid flowing downward flows down at slow speeds since many micro regions
existing in acute forms between the meshes of the nets and the heat
transfer plate make the liquid stay temporarily and since the existence of
meshes of the nets causes the liquid flowing downward along the heat
transfer plates to spread horizontally, not allowing the liquid to
collecting on particular spots. In addition, as a result of the nets being
adhered to the heat transfer plates, the surface of the liquid staying at
meshes is successively renewed or replaced by the liquid flowing downward,
so that the liquid is highly efficiently brought into contact with a gas
rising from a site below through passages between the heat transfer
plates. In addition, the exothermic or endothermic heat usually
accompanied by the gas-liquid contact process can be taken off directly at
positions where it is generated by the heat medium inside the heat
transfer plates, achieving highly efficient heat exchange. In consequence,
it is possible to provide a gas-liquid contacting heat exchanger which
presents markedly excellent performances by virtue of both the high
gas-liquid contact efficiency and the high heat exchange efficiency.
Further scope of applicability of the present invention will become
apparent from the detailed description given hereinafter. However, it
should be understood that the detailed description and specific examples,
while indicating preferred embodiments of the invention, are give by way
of illustration only, since various changes and modifications within the
spirit and scope of the invention will become apparent to those skilled in
the art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed
description given hereinbelow and the accompanying drawings which are
given by way of illustration only, and thus are not limitative of the
present invention and wherein:
FIG. 1 is a sectional view showing an embodiment of a gas-liquid contacting
apparatus of the present invention;
FIG. 2 is an enlarged perspective view of a heat pipe as a constituent of a
gas-liquid contacting apparatus of the present invention;
FIG. 3 is a perspective view showing another embodiment of a gas-liquid
contacting apparatus of the present invention;
FIG. 4 is a schematic perspective view showing a heat exchanger of
gas-liquid contacting plate type in accordance with the present invention;
FIG. 5 is a schematic side section of the heat exchanger of FIG. 4;
FIG. 6 is a schematic diagram showing an example of applying a heat
exchanger of gas-liquid contacting plate type of the present invention to
a CO.sub.2 regeneration tower;
FIG. 7 is a sectional view showing an example of a heat exchanger utilizing
conventional heat pipes; and
FIG. 8 is a perspective view showing a heat exchanger utilizing
conventional heat pipes.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First of all, embodiments relating to first to third features of the
present invention will be described with reference to FIGS. 1 to 3.
FIG. 2 is an enlarged perspective view showing fins and a part of a heat
pipe of the present invention to be applied to a gas-liquid contacting
apparatus shown in FIG. 3 described later. In FIG. 2, fins 22 are attached
to the barrel side of a heat pipe 21 in such a manner that the fins may be
perpendicular to the axis of the heat pipe 21. The fin 22 is made up of a
metal plate 23 and nets 24 adhered to both side surfaces of the metal
plate 23. As a way of weaving the net 24, any of various weaves inclusive
of plane weave, twill weave etc., can be used. The metal plate 23 is
preferably made of a material which has a good thermal conductivity and
will not be eroded by the gas and liquid to be processed.
No particular restriction is put on a technique for adhering the net 24 on
the plate 23, and any means such as welding or bonding can be utilized, as
long as the net will not peel off in the state where the pipe is used in a
gas-liquid contacting apparatus that also serves as a heat exchanger, as
shown in FIG. 3. The net 24 is preferably made of a material which will
not be eroded by the gas and liquid to be contacted with one another. For
example, a single-core wire mesh, a single-core plastic net, or any net
made up of other materials may be utilized. The net 24 may be disposed so
that the wires of the net 24 may be placed at a different angle to the
ground. The size of the mesh of the net to be selected is preferably 3
mesh or more, more preferably 8 mesh or more. The heat pipe of the present
invention must be provided with the fins at least on either the heat
collecting section side or the radiating section side, and is preferably
provided with fins made of the aforementioned material on both sides.
FIG. 3 shows an embodiment of a gas-liquid contacting apparatus of the
present invention. The configuration of the apparatus is similar to the
prior art apparatus shown in FIG. 8 except the structure of fins.
Specifically, in the apparatus of the present invention, a large number of
the aforementioned heat pipes with fins are gathered with the pipe axes
being approximately horizontal (inclusive of horizontal) so that the fins
of the heat pipes may be positioned on an approximately vertical plane
(inclusive of vertical plane) while a partitioning plate 25 is provided to
separate the heat collecting section and the radiating section. In this
case, the fin made of metal plate with nets adhered on both sides thereof
serves as gas-liquid contacting wall surfaces for bringing the liquid
flowing downward from a site above the fins into contact with the gas
supplied from a site below the fins or from the side of the fins.
FIG. 1 is a sectional view showing a configuration in which the vertically
formed fins in FIG. 2 are joined forming vertical plates. That is, a large
number of heat pipes are made to penetrate the thus vertically formed
plates at right or approximately right angles so that the thus vertically
formed joined fins serve as the contacting surface walls for bringing the
liquid flowing downward into contact with the gas.
Referring to FIG. 1, when a high temperature air containing, for example,
ethanol is introduced into the gas-liquid contacting apparatus from a
bottom side of the apparatus, the air is cooled, as rising, by a large
number of the fins attached to a large number of the heat pipes joined,
whereby the ethanol component condenses and flows down along the fins
joined. In this case, since the surfaces of the fins are composed by metal
plates with nets adhered thereto, the condensed ethanol spreads
horizontally as flowing down. Therefore, the contacting area of the
ethanol with air supplied is enlarged. In consequence, the rising air is
cooled down on the surfaces of fins by virtue of heat exchange effect
while the condensed ethanol is efficiently brought into contact with the
rising air containing ethanol fed from the bottom side for performing
gas-liquid contact, whereby the ethanol reevaporates so as to further
promote the heat exchange.
A radiating section of heat pipes is formed on the right side of the
partitioning plate 25 shown in FIG. 1. That is, the operating liquid
inside the heat pipes is cooled and condensed by, for example,
low-temperature water that flows down from the upper site, so that the
condensed operating liquid moves to the left inside the heat pipe to serve
again to cool the high-temperature air containing ethanol. In the case of
FIG. 1, no fins are provided for the pipes to be cooled in the radiating
section on the right side of the partitioning plate, but the fins shown in
FIG. 2 or the joined fins present in the heat collecting section shown in
FIG. 1 may be provided.
The heat pipe proposed by the present invention as well as the gas-liquid
contacting apparatus using the heat pipes of the present invention can be
applied not only to the cooling and condensation process of vapor
described as to FIG. 1, but also can be applied widely to various
gas-liquid containing apparatuses and processes involving heat exchange
for production of chemical products in manufacturing factories. Examples
of such processes include distillation, evaporation, gas-absorption,
humidity control etc.
According to the heat pipe and the gas-liquid contacting apparatus using
the heat pipes as described above as to first to third configurations of
the present invention, the liquid flowing down does not go down linearly
over the gas-liquid contact surface, but spreads out over the contact
surface, so that the staying time of the liquid taken for flowing down
becomes longer resulting in markedly improved gas-liquid contacting
efficiency. Further, the long stay of the liquid on the contacting surface
allows the heat pipes to exchange heat during the gas-liquid contact.
Referring next to FIGS. 4 to 6, a fourth configuration in accordance with
an embodiment of the present invention will be described.
Initially, FIGS. 4 and 5 are to be referred. FIGS. 4 and 5 are perspective
and side views schematically illustrating a principle of a heat exchanger
of gas-liquid contacting plate type. A heat exchanger 2 of gas-liquid
contacting plate type in accordance with the present invention is composed
of, as shown in figures, a large number of heat transfer plates 4 placed
vertically in parallel with one another, passages 10 formed inside the
heat transfer plates 4 for introducing a heat medium C, gas passages 20
formed between the heat transfer plates 4, and nets 30 provided on the
outside surfaces of the heat transfer plates 4 or on the side surfaces
facing the gas passages.
The heat transfer plate 4 is made up of a metal having a good thermal
conductivity and has hollow inside forming the passage 10 for the heat
medium to be described below. FIGS. 4 and 5 show only three heat transfer
plates 4 for simplifying the illustrations, but in practice, a larger
number of heat transfer plates 4 are disposed at certain intervals and
supported by means of rigidity of pipes 6 or with the help of
unillustrated spacers, as required. The insides of these heat transfer
plates 4 communicate with each other through the pipes 6, and the heat
medium C flows in directions shown by arrows in FIG. 5. In the example
illustrated, the pipes 6 are connected so that the heat medium C flows in
the same direction (downward) through the inside of all the heat transfer
plates 4, but it is possible to provide the pipes 6 so as to alternate the
directions of flow of the heat medium C inside the plates 4. The heat
medium C is unlikely to leak if joints between the heat transfer plates 4
and the pipes 6 are welded, though welding makes it difficult to
disassemble the heat exchanger for maintenance. In general, the heat
transfer plates 4 and pipes 6 are jointed by fitting gaskets therebetween
and fixing with screws etc., in order to make easy the maintenance and
repairs of the apparatus.
The net 30 adhered to the heat transfer plate 4 is preferably made of a
material that will not be eroded by the gas and liquid to be subjected to
the gas-liquid contact. For example, the net may be formed by a wire mesh,
a plastic net etc. The weaving manner of the net 30 illustrated is plain
weave, but this weave is not limited and any other various weaves
inclusive of twill weave can be used. No particular restriction is put on
a technique for adhering the net 30 onto the heat transfer plate 4. The
net 30 may be disposed so that the wires of the net 30 may be placed at a
different angle to the ground. The size of the mesh of the net to be
selected is preferably 3 mesh or more, more preferably 8 mesh or more.
Next, the operation of the thus constructed heat exchanger of gas-liquid
contacting plate type will be briefed. In FIG. 5, a gas G to be subjected
for the gas-liquid contact rises upward through the air passages 20 formed
between heat transfer plates 4 while a liquid L for the gas liquid contact
is made to flow down cascade-wise from the upper site of the heat transfer
plates 4. Since nets 30 are adhered onto the side faces of heat transfer
plates 4, the liquid L, as flowing downward along the side faces of heat
transfer plates 4, mainly tends to stay in micro regions defined in acute
forms between horizontally extending portions of the net 30 and the side
surface of the heat transfer plate. Further, as the liquid flows down over
the net 30, the surface part of the staying liquid is successively renewed
by newly coming liquid. Thus, since the liquid L spreads horizontally and
stays and since the surface part of the liquid is successively renewed,
the liquid L is exposed on the surfaces of heat transfer plates 4 and may
come into contact at a high-efficiency with the gas G rising. On the other
hand, the predetermined heat medium C flows inside heat transfer plates 4
so as to directly heat or cool the liquid L flowing downward along the
heat transfer plates 4.
In the case where only a gas containing a condensible substance is made to
pass and be cooled while no liquid L is made to flow down from above the
heat transfer plates 4, the condensible component in the gas, e.g., water
in a combustion exhaust gas is condensed by taking off the condensing
latent heat of the condensible component in the gas by way of the heat
medium C inside the heat transfer plates 4. The condensed component then
adheres to nets 30 as well as onto the side faces of heat transfer plates
4. As increasing in quantity, the condensed water adhered gradually flows
downward. The condensed component spreads laterally over vertical faces
formed of the nets 30 and heat transfer plates 4, so as to be brought into
contact with the high temperature combustion exhaust gas fed from the
lower site of the apparatus. In this way, the combustion exhaust gas may
be cooled efficiently. The condensed water component in this case finally
drains off downward from the heat exchanger of gas-liquid contacting plate
type. Heat transfer caused in the gas-liquid contact process involves, in
addition to the condensing latent heat, the heat of reaction arising in
the gas-liquid contact. The cases where the reaction is exothermic are
represented by the aforementioned case in which CO.sub.2 component in the
combustion exhaust gas is absorbed by the amine solution. In such a case,
the generated heat is directly taken off by way of the heat medium C
flowing inside the heat transfer plates 4, thereby preventing rise in
temperature of the contacting gas and liquid so as to avoid lowering of
the equilibrium constant. In this way, a highly efficient gas-liquid
contacting process can be achieved. In the case of absorbing reaction, the
situation becomes opposite, so heat inside the heat transfer plates 4 is
transferred to the gas-liquid contact side.
Next, referring to FIG. 6, description will be made on an example in which
the heat exchanger of gas-liquid contacting plate type of the present
invention is applied to a regeneration tower for regenerating amine
absorbent solution by recollecting CO.sub.2 from the amine absorbent
solution which has absorbed CO.sub.2 (to be referred to as CO.sub.2 -rich
amine absorbent solution hereinbelow). In this example, the same
components with those shown in FIGS. 4 and 5 are assigned with the same
reference numerals and the nets 30 shown are simplified in the figure. In
FIG. 6, two heat exchangers of gas-liquid contacting plate type of the
present invention are mounted in upper and lower sites inside a
regeneration tower 50. In the upper heat exchanger 2a, low-temperature
cooling water is introduced as a heat medium in heat transfer plates 4a
which constitute the upper heat exchanger 2a, in order that amine
contained in a slight amount in the CO.sub.2 gas rising through air
passages 20a may be prevented from discharging outside the tower. On the
other hand, high-temperature steam is introduced as a heat medium in the
heat transfer plates 4b constituting the lower heat exchanger 2b, in order
to regenerate the absorbent solution by separating CO.sub.2 from the
CO.sub.2 -rich amine absorbent solution. Provided between both the heat
exchangers 2a and 2b is a nozzle 52 which sprays over the lower heat
exchanger 2b the CO.sub.2 -rich amine absorbent solution delivered from an
unillustrated CO.sub.2 absorption tower. An absorbent solution reservoir
54 for receiving regenerated amine absorbent solution having a low
concentration of CO.sub.2 is provided at the bottom of the regeneration
tower 50.
The CO.sub.2 -rich amine absorbent solution sprayed from the nozzle 52,
together with condensed water (to be described later) which comes down
from the upper heat exchanger 2a, gradually flows downward along heat
transfer plates 4b having nets 30 adhered thereto in the lower heat
exchanger 2b. In this situation, high-temperature steam circulates inside
the heat transfer plates 4b, so that the CO.sub.2 -rich amine absorbent
solution is heated efficiently. Therefore, as steam is generated from the
amine absorbent solution, gaseous CO.sub.2 is released together with the
steam. The gaseous substances, rising through the air passages 20b, are
brought into contact with the CO.sub.2 -rich amine absorbent solution
since the solution is made to flow down continuously from the upper site.
As a result, the steam generated and the CO.sub.2 -rich amine absorbent
solution come into contact with one another on heat transfer plates 4b
with nets 30 adhered thereto, whereby the CO.sub.2 component is further
promoted to separate from the steam, both released from the CO.sub.2 -rich
amine absorbent solution. The heat energy required for this process is
supplied continuously from the flowing steam inside the heat transfer
plates 4b as described above. In consequence, both the gas-liquid contact
process and the heat exchange process are simultaneously carried out
highly efficiently. The thus regenerated amine aqueous solution with
CO.sub.2 component removed therefrom is then temporarily reserved in the
recollected solution reservoir 54 disposed in the lower portion.
Thereafter, the reserved solution is discharged, as required, by a pump 56
into the absorption tower so as to be reused therein as a regenerated
amine solution.
On the other hand, the CO.sub.2 component released from CO.sub.2 -rich
amine absorbent solution, together with the steam, rises upward through
air passages 20a between heat transfer plates 4a in the upper heat
exchanger 2a. In this while, the gas passing through air passages 20a is
cooled since cooling water is circulated inside the heat transfer plates
4a. Therefore, the steam component condenses on heat transfer plates 4a
with nets 30 adhered thereto and flows downward slowly along the plates.
The condensed water flowing downward, while exchanging heat with the
cooling water inside the heat transfer plates 4a, comes into contact with
(or performing gas-liquid contact with) the aforementioned gas rising
upward from the lower heat exchanger 2b. Therefore, the gas rising is
cooled by the gas-liquid contact whereby the amine component can be
prevented from discharging outside the tower. In this way, also in the
upper heat exchanger 2a, the gas-liquid contact and the heat exchange are
simultaneously achieved highly efficiently. The gas rising upward and
passing through the air passages 20a of the heat exchanger 2a is reduced
in steam component and delivered to a next step as a CO.sub.2 -rich gas.
In the conventional regeneration tower, the gas mixture of CO.sub.2 and
steam delivered from the upper portion of the tower is cooled by a
separately provided heat exchanger, in place of the heat exchanger 2a of
the present invention and the thus condensed water is sprayed from a
nozzle at the top of the tower so as to prevent amine component from
discharging outside the tower. Further, in place of the heat exchanger 2b,
a part of regenerated amine is extracted from the tower and heated outside
the tower to form steam, which is in turn fed to the tower bottom so as to
strip off CO.sub.2 component with steam (by steam-stripping) from the
CO.sub.2 -rich amine absorbent solution to thereby regenerate the
absorbent solution. Thus, the conventional regeneration tower would
require a separate heat exchanger and a heater outside the tower,
complicating the structure of the apparatus. Moreover, the heat exchanging
efficiency was not enough to satisfy the demands. In contrast, the use of
the heat exchanger of gas-liquid contacting plate type of the present
invention can execute both the gas-liquid contact and the heat exchange
simultaneously, so that the structure of the chemical plant can be
markedly simplified and it is possible for the apparatus to run at high
heat exchange efficiency.
As has been detailed heretofore, according to the heat exchanger of
gas-liquid contacting plate type of the present invention (the forth
configuration of the present invention), the contacting area between the
gas and the liquid flowing downward along the heat transfer plates is
increased by virtue of providing the nets. In addition, the nets hold the
liquid so as to linger the staying time of the liquid that flows downward,
so that the gas-liquid contacting efficiency is enhanced to a great degree
with a markedly increased heat exchange efficiency. Further, the
configuration of the apparatus can be made compact, so this feature
contributes to save the space required for the plant to a great extent.
The invention being thus described, it will be obvious that the same may be
varied in many ways. Such variations are not to be regarded as a departure
from the spirit and scope of the invention, and all such modifications as
would be obvious to one skilled in the art are intended to be included
within the scope of the following claims.
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